Metal work cutting tools generally include a disposable cutting insert and a toolholder adapted to firmly hold the cutting insert. The cutting insert is brought into contact with a metal workpiece while the workpiece is rotated to remove a chip from the workpiece. There is a tendency for removed chips to form long, continuous strands rather than break into small segments. These long strands spiral and cause hot metal liberated from the workpiece to remain in contact with the cutting insert for a longer duration and often tangle up with the workpiece or the toolholder. If the strand tangles up with the workpiece or the toolholder, the operation must be halted so that the strand may be manually broken. As most metal working operations are intended to operate nearly automatically, this is a very undesirable and expensive task. Furthermore, the life of a cutting insert, generally being formed from carbide steel or a similar metal, is heavily dependent upon operation temperature. Under normal conditions, the cutting insert is exposed to intense heat generated in cutting chips from the workpiece. This heat is significantly increased when hot metal chips remain in contact with the cutting insert for an extended duration as they do when the chips form continuous strands.
The need to break chips to avoid stranding is well understood and recognized in the metal working industry. A great deal of design and experimentation has been devoted to the development of efficient and effective means for breaking chips. For example, some inserts are designed with integrally formed chip-breakers. Such chip-breakers usually comprise an obstruction in the path of the chip for deflecting and curling the chip. By bending the chip to the limit of its ductility, the chip breaks into small segments.
Another method of chip-breaking is to direct a high velocity stream of coolant at the chip. The stream bends the chip and cools it, making it more brittle. This combination of effects causes the chips to break off into smaller segments rather than form long strands. The coolant also serves to cool the cutting insert thereby extending its operational life.
Methods have been developed for directing a high velocity fluid stream at the cutting insert which use an external fluid line attached to the toolholder. Often, several tools will be used to work on a single workpiece, necessitating changing of the toolholders. The additional steps of disconnecting and reconnecting the external fluid line significantly decrease the speed and efficiency of toolholder replacement.
A tool assembly disclosed in U.S. Pat. No. 4,955,264, has been developed which obviates the need for an external fluid line. This tool assembly includes a coolant passage formed in the toolholder and a cap having a constricted outlet attached to the outlet of the passageway. While this apparatus solves the problem of conventional tool assemblies, it has a significant limitation. Often a single tool assembly may be used to make several different cuts on a workpiece. These different cuts may be at different depths, angles, and/or directions. As a result, different portions of the cutting insert contact the workpiece and the removed chips differ in character. For different cuts, it is desirable to alter the direction of the high velocity coolant stream to provide optimal flow across the insert and against the chip. In the described design, the direction of the coolant stream may only be altered by changing caps, each cap outlet having a particular angle of inclination to the cutting insert.
Therefore, there is a need for conveniently and efficiently adjusting the direction of the high velocity coolant stream from a coolant supply system forming an integral part of a toolholder.